K. A. Jones in "Laser Assisted MOCVD Growth", in Solid State Technology, 28(10), 151-156 (1985) indicates that metals can be deposited by allowing molecules to absorb ultraviolet light citing the earlier work of T. F. Deutsch et al. in Appl. Phys. Lett. 1979, 35(2), 175-177. The laser photodeposition of metal films by Deutsch et al. utilized the ultraviolet laser-induced photodissociation of organometallic compounds to yield features smaller than 2 microns. Deutsch et al. use trimethylaluminum and dimethylcadmium as parent gases from which aluminum or cadmium were deposited. They also employed a methyltin and CF.sub.3 I to deposit tin and iodine.
U.S. Pat. Nos. 4,559,237 and 4,619,838 indicate that various inorganic metal species in the form of either simple or complex salts can be deposited onto semiconductor powders by means of a photoredox reaction by irradiation of a suspension of a semiconductor powder in the presence of oxygen and, optionally, carbon dioxide in an oxidizable system (e.g., water, an alkanol, an ether, etc.) which protects the semiconductor from photocorrosion.
Japanese Patent Publication Nos. 243279/1985 and 243280/1985 prepare transparent electrodes by forming an electrode-forming solution of a non-hydrolyzable organic metal compound containing indium and tin (e.g., trisacetylacetonatoindium and bis-acetylacetonatodibutyltin), an organic binder (e.g., a cellulose), and a solvent (e.g., a high boiling solvent to form a paste for screen printing or a low boiling solvent for a dipping solution). The desired substrate is treated with the solution and irradiated with ultraviolet radiation. The resulting ozone which is produced causes organic chain decomposition and forced oxidation of the solution thereby facilitating the burning of its organic components so that a film of uniform quality is formed.
Japanese Patent Publication No. 50172/1985 describes dipping an electrically non-conductive substance carrying a semiconductor on its surface into a solution containing metal ions derived from inorganic metal salts. The semiconductor is excitable by visible and/or ultraviolet light. An electron donor can be used to assist in the injection of electrons into the semiconductor when the latter is excited by light and the metal ions are reduced to the metal state. This reference describes the use of electron donor compounds such as ammonia, amines, alcohols, aldehydes, ketones, ethers, sulfoxides and amides to enable the injection of electrons into the semiconductor. Preferred examples are identified as being ammonia, methylamine, methanol, and ethanol.
Japanese Patent Publication No. 133076/1987 describes a process for forming metal-plated inorganic substances by dispersing an inorganic substance in a solution containing ions of a catalytic metal (e.g., derived from palladium chloride) and a reaction assistant (or reducing agent), irradiating the dispersion with light to cause reduction of the ions so that the catalytic metal may be deposited on the surface of the inorganic substance and then plating the surface of the inorganic substance with a metal electrolessly. Various reducing agents are identified as reaction assistants including alcohols, aldehydes, sugars, amines (e.g., ethylamine, benzylamine, and aniline), organic acids, and oxoacid salts containing either phosphorus, sulfur or nitrogen.
A series of publications by Y. L. Chow et al. (e.g., J. Chem. Soc. Perkin Trans. II 1986, pp. 365-369 and the citations therein) relate to the photoreduction of bis(acetylacetonato) copper(II) and nickel (II) using benzene or certain high triplet energy ketones, e.g., xanthen-9-one, benzophenone, or acetophenone.